Tag Archives: holograms

Edible nano-structured holograms could decorate food one day

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Caption Nanostructures (yellowish-green images; scale bar, 5 μm) were patterned onto dried corn syrup films, producing edible, rainbow-colored holograms (scale bar, 2 mm). Credit Adapted from ACS Nano 2021, DOI: 10.1021/acsnano.0c02438

Where food safety is concerned, much of the research I’ve seen is focused on adding senors to the packaging rather than direct application to the foodstuff but this is different, from a February 17, 2021 news item on phys.org,

Holograms are everywhere, from driver’s licenses to credit cards to product packaging. And now, edible holograms could someday enhance foods. Researchers reporting in ACS [American Chemical Society] Nano have developed a laser-based method to print nanostructured holograms on dried corn syrup films. The edible holograms could also be used to ensure food safety, label a product or indicate sugar content, the researchers say.

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A February 17, 2021American Chemical Society news release (also on EurekAlert), which originated the news item,

Most holograms are imprinted with lasers onto metal surfaces, such as aluminum, but the materials aren’t edible. For foods, holograms made with nanoparticles have been proposed, but the tiny particles can generate reactive oxygen species, which might be harmful for people to eat. In a different approach, food scientists have molded edible holograms onto chocolate, but the process only works for certain types of the confection, and a different mold is needed for each hologram design. Bader AlQattan, Haider Butt and colleagues wanted to find a safe, fast and versatile way to pattern edible holograms onto a variety of foods.

To develop their method, the researchers made a solution of corn syrup, vanilla and water and dried it into a thin film. They coated the film with a fine layer of non-toxic black dye. Then, they used a technique called direct laser interference patterning to etch off most of the dye, leaving behind raised, nanoscale lines that formed a diffraction grating. When struck by light, the nanostructure diffracted the light into a rainbow pattern, with different colors appearing at different angles of viewing. The team could control the intensity and range of colors by varying the spacing between lines in the grating or the sugar content of the corn syrup film. Before edible holograms are ready to hit store shelves, however, the researchers want to adapt the method to a food-grade dye that could replace the synthetic black dye used in these pilot experiments.

Here’s a link to and a citation for the paper,

Direct Printing of Nanostructured Holograms on Consumable Substrates by Bader AlQattan, Joelle Doocey, Murad Ali, Israr Ahmed, Ahmed E. Salih, Fahad Alam, Magdalena Bajgrowicz-Cieslak, Ali K. Yetisen, Mohamed Elsherif, and Haider Butt. ACS Nano 2021, 15, 2, 2340–2349 DOI: https://doi.org/10.1021/acsnano.0c02438 Publication Date:February 1, 2021 Copyright © 2021 American Chemical Society

This paper appears to be open access.

It seems these scientists are also considering the aesthetic possibilities. Ffrom the paper, Note: Links have been removed,

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The use of holograms in food could potentially improve sensory appeal [emphasis mine] and, through biosensing, could increase health and safety.(1,2) Holograms can even be used to store information as edible microtags.(3) They are also attractive to the eye as they produce rainbow patterns with light. Using edible holograms on foods, not only as decoration but also to sense harmful bacteria, could improve food quality/lifetime monitoring.(4,5) Food holograms which signify a qualitative information about the sugar contents could be of value in controlling the sugar consumption, that is challenging to be measured at the moment.(6)

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As it is, I find food pretty attractive. So, I’m not sure why there’s a need to improve its sensory appeal. On the other hand, I can’t argue with increased food safety.

Should you be interested in more about holograms and their current applications, including chocolate decoration, you can check out Michael Berger’s February 17, 2021 Nanowerk Spotlight article.

Holographic chocolate surfaces. (Image: Morphotonix) [downloaded from https://www.nanowerk.com/spotlight/spotid=57310.php]

What do you think about decorating food with holograms? If you feel inclined, do let me know in the comments.

Hologram with nanostructures could improve fraud protection

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This research on holograms comes from Harvard University according to a May 13, 2016 news item on ScienceDaily,

Holograms are a ubiquitous part of our lives. They are in our wallets — protecting credit cards, cash and driver’s licenses from fraud — in grocery store scanners and biomedical devices.

Even though holographic technology has been around for decades, researchers still struggle to make compact holograms more efficient, complex and secure.

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences have programmed polarization into compact holograms. These holograms use nanostructures that are sensitive to polarization (the direction in which light vibrates) to produce different images depending on the polarization of incident light. This advancement, which works across the spectrum of light, improves anti-fraud holograms as well as those used in entertainment displays.

A May 13, 2016 Harvard University press release (also on EurekAlert) by Leah Burrows, which originated the news item, provides more detail,

“The novelty in this research is that by using nanotechnology, we’ve made holograms that are highly efficient, meaning that very little light is lost to create the image,” said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering and senior author of the paper. “By using incident polarized light, you can see far a crisper image and can store and retrieve more images. Polarization adds another dimension to holograms that can be used to protect against counterfeiting and in applications like displays.”

Harvard’s Office of Technology Development has filed patents on this and related technologies and is actively pursuing commercial opportunities.

Holograms, like digital photographs, capture a field of light around an object and encode it on a chip. However, photographs only record the intensity of light while holograms also capture the phase of light, which is why holograms appear three-dimensional.

“Our holograms work like any other but the image produced depends on the polarization state of the illuminating light, providing an extra degree of freedom in design for versatile applications,” said Mohammadreza Khorasaninejad, postdoctoral fellow in the Capasso Lab and first author of the paper.

There are several states of polarization. In linearly polarized light the direction of vibration remains constant while in circularly polarized light it rotates clockwise or counterclockwise. The direction of rotation is the chirality.

The team built silicon nanostructured patterns on a glass substrate, which act as superpixels. Each superpixel responds to a certain polarization state of the incident light. Even more information can be encoded in the hologram by designing and arranging the nanofins to respond differently to the chirality of the polarized incident light.

“Being able to encode chirality can have important applications in information security such as anti-counterfeiting,” said Antonio Ambrosio, a research scientist in the Capasso Lab and co-first author. “For example, chiral holograms can be made to display a sequence of certain images only when illuminated with light of specific polarization not known to the forger.”

“By using different nanofin designs in the future, one could store and retrieve far more images by employing light with many states of polarization,” said Capasso.

Because this system is compact, it has application in portable projectors, 3D movies and wearable optics.

“Modern polarization imaging systems require cascading several optical components such as beam splitters, polarizers and wave plates,” said Ambrosio. “Our metasurface can distinguish between incident polarization using a single layer dielectric surface.”

“We have also incorporated in some of the holograms a lens function that has allowed us to produce images at large angles,” said Khorasaninejad. “This functionality combined with the small footprint and lightweight, has significant potential for wearable optics applications.”

Here’s a link to and a citation for the paper,

Broadband and chiral binary dielectric meta-holograms by Mohammadreza Khorasaninejad, Antonio Ambrosio, Pritpal Kanhaiya, and Federico Capasso. Science Advances  13 May 2016: Vol. 2, no. 5, e1501258 DOI: 10.1126/sciadv.1501258

This paper is open access.

A strange state of light

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Apparently combining a hologram with subwavelength structures at a scale of just tens of nanometers can lead to ‘strange’ light. From the Aug. 20, 2013 news item on Nanowerk,

Applied physicists at the Harvard School of Engineering and Applied Sciences (SEAS) have demonstrated that they can change the intensity, phase, and polarization of light rays using a hologram-like design decorated with nanoscale structures.

As a proof of principle, the researchers have used it to create an unusual state of light called a radially polarized beam, which—because it can be focused very tightly—is important for applications like high-resolution lithography and for trapping and manipulating tiny particles like viruses.

The Aug. 20, 2013 Harvard University news release by Manny Marone, which originated the news item, further describes the device and the effect (Note: A link has been removed),

This is the first time a single, simple device has been designed to control these three major properties of light at once. (Phase describes how two waves interfere to either strengthen or cancel each other, depending on how their crests and troughs overlap; polarization describes the direction of light vibrations; and the intensity is the brightness.)

“Our lab works on using nanotechnology to play with light,” says Patrice Genevet, a research associate at Harvard SEAS and co-lead author of a paper published this month in Nano Letters. “In this research, we’ve used holography in a novel way, incorporating cutting-edge nanotechnology in the form of subwavelength structures at a scale of just tens of nanometers.” One nanometer equals one billionth of a meter.

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Using these novel nanostructured holograms, the Harvard researchers have converted conventional, circularly polarized laser light into radially polarized beams at wavelengths spanning the technologically important visible and near-infrared light spectrum.

“When light is radially polarized, its electromagnetic vibrations oscillate inward and outward from the center of the beam like the spokes of a wheel,” explains Capasso [Federico Capasso, professor of applied physics]. “This unusual beam manifests itself as a very intense ring of light with a dark spot in the center.”

“It is noteworthy,” Capasso points out, “that the same nanostructured holographic plate can be used to create radially polarized light at so many different wavelengths. Radially polarized light can be focused much more tightly than conventionally polarized light, thus enabling many potential applications in microscopy and nanoparticle manipulation.”

The new device resembles a normal hologram grating with an additional, nanostructured pattern carved into it. Visible light, which has a wavelength in the hundreds of nanometers, interacts differently with apertures textured on the ‘nano’ scale than with those on the scale of micrometers or larger. By exploiting these behaviors, the modular interface can bend incoming light to adjust its intensity, phase, and polarization.

Here’s a link to and a citation for the published paper,

Nanostructured Holograms for Broadband Manipulation of Vector Beams by Jiao Lin, Patrice Genevet, Mikhail A. Kats, Nicholas Antoniou, and Federico Capasso. Nano Lett., Article ASAP DOI: 10.1021/nl402039y Publication Date (Web): August 5, 2013
Copyright © 2013 American Chemical Society

This article is behind a paywall.

I last wrote about Federico Carpasso’s work in an Oct. 16, 2013 posting, Harvard researchers look deeply into oily puddles as they rethink thin films and optical loss.

Reimagining prosthetic arms; touchable holograms and brief thoughts on multimodal science communication; and nanoscience conference in Seattle

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Reimagining the prosthetic arm, an article by Cliff Kuang in Fast Company (here) highlights a student design project at New York’s School of Visual Arts. Students were asked to improve prosthetic arms and were given four categories: decorative, playful, utilitarian, and awareness. This one by Tonya Douraghey and Carli Pierce caught my fancy, after all, who hasn’t thought of growing wings? (Rrom the Fast Company website),

Feathered cuff and wing arm

Feathered cuff and wing arm

I suggest reading Kuang’s article before heading off to the project website to see more student projects.

At the end of yesterday’s posting about MICA and multidimensional data visualization in spaces with up to 12 dimensions (here)  in virtual worlds such as Second Life, I made a comment about multimodal discourse which is something I think will become increasingly important. I’m not sure I can imagine 12 dimensions but I don’t expect that our usual means of visualizing or understanding data are going to be sufficient for the task. Consequently, I’ve been noticing more projects which engage some of our other senses, notably touch. For example, the SIGGRAPH 2009 conference in New Orleans featured a hologram that you can touch. This is another article by Cliff Kuang in Fast Company, Holograms that you can touch and feel. For anyone unfamiliar with SIGGRAPH, the show has introduced a number of important innovations, notably, clickable icons. It’s hard to believe but there was a time when everything was done by keyboard.

My August newsletter from NISE Net (Nanoscale Informal Science Education Network) brings news of a conference in Seattle, WA at the Pacific Science Centre, Sept. 8 – 11, 2009. It will feature (from the NISE Net blog),

Members of the NISE Net Program group and faculty and students at the Center for Nanotechnology in Society at Arizona State University are teaming up to demonstrate and discuss potential collaborations between the social science community and the informal science education community at a conference of the Society for the Study of Nanoscience and Emerging Technologies in Seattle in early September.

There’s more at the NISE Net blog here including a link to the conference site. (I gather the Society for the Study of Nanoscience and Emerging Nanotechnologies is in its very early stages of organizing so this is a fairly informal call for registrants.)

The NISE Net nano haiku this month is,

Nanoparticles

Surface plasmon resonance
Silver looks yellow

by Dr. Katie D. Cadwell of the University of Wisconsin-Madison MRSEC.

Have a nice weekend!